A motor to be used in a blower of an on-vehicle air conditioner has not any more employed ball bearings at both ends of a shaft because this motor should be downsized. Instead of employing the ball bearings, a rotor and a stator are disposed with a given distance between a magnetic center of the rotor and a magnetic center of the stator along an axial direction of the shaft. This structure allows magnetic restoring force to act between the rotor and the stator. This magnetic restoring force (hereinafter simply referred to as restoring force) causes both of the magnetic centers along the axial direction to agree with each other, and this restoring force allows the shaft to push a thrust plate with its end called as a pivot.
In a case where the on-vehicle air conditioner is installed in a variety of vehicles, a difference occurs in gravity acting direction depending on an installation state of the on-vehicle air conditioner. However, use of a structure where the restoring force discussed above is used allows not changing a positional relation between the rotor and the stator along the axial direction of the shaft even if the difference occurs in the gravity acting direction. As a result, a steady motor function is obtainable. The thrust plate is mounted to a housing of the motor. (Refer to, e.g. Patent Literature 1.)
Use of the foregoing conventional motor in the on-vehicle air conditioner, however, encounters the following problems: For instance, in a case where a conventional air conditioner is mounted to a car, when the car runs on a bad road or bumps on a road, force greater than and opposite to the restoring force is sometimes applied to the shaft. As a result, the shaft leaves the thrust plate instantaneously, and when the force greater than the restoring force disappears; the shaft tries to return to its original position with the aid of the restoring force. At this time, the shaft hits the thrust plate, and a collision sound is generated between the shaft and the thrust plate.    Patent Literature 1: Unexamined Japanese Patent Application Publication No. 2007-100600